Superhard cutter with spikes

ABSTRACT

A cutter for use with a drill bit includes: a substrate for mounting in a pocket of the drill bit and made from a cermet material; and a cutting table made from a polycrystalline superhard material, mounted to the substrate, and including a set of spikes formed along at least a portion of a side of the cutting table. Each spike has an apical edge extending above a working face of the cutting table and converging toward the working face as the spike extends from the side of the cutting table across at least a portion of the working face. Each spike has a pair of base edges converging toward the apical edge as the spike extends from the side of the cutting table thereacross, thereby forming a progressively wider gap between adjacent spikes.

BACKGROUND OF THE DISCLOSURE Field of the Disclosure

The present disclosure generally relates to a superhard cutter withspikes.

Description of the Related Art

U.S. Pat. No. 4,984,642 discloses a composite tool including a sinteredmetal carbide support and a polycrystalline diamond active part havingan inner surface of metallurgical connection to the support and anoutwardly facing working surface. The working surface comprisescorrugations which are substantially parallel to one another and formsuccessive projecting zones and hollow zone on at least a part of theworking surface. The composite tool is in particularly intended fordrilling to a great depth, such as drilling oil wells.

U.S. Pat. No. 6,065,554 discloses a preform cutting element for a rotarydrag-type drill bit comprises a front facing table of superhard materialhaving a front surface, a peripheral surface, a rear surface bonded to asubstrate of less hard material, and a cutting edge formed by at leastpart of the junction between the front surface and the peripheralsurface. The front surface of the facing table is formed with achip-breaking formation which is located adjacent the cutting edge andis shaped to deflect transversely of the front surface of the facingtable cuttings which, in use, are removed by the cutting edge from theformation being drilled. The chip-breaking formation may comprise aperipheral groove or rebate, or an upstanding ridge or insert.

U.S. Pat. No. 8,936,115 discloses a cutting table including a cuttingsurface, an opposing surface, a cutting table outer wall, and one ormore fins. The cutting table outer wall extends from the circumferenceof the opposing surface to the circumference of the cutting surface. Thefins extend from a portion of the cutting surface to a portion of thecutting table outer wall. The cutting table is optionally leached priorto forming the fins. One or more fins are positioned in parallel with atleast another fin in some embodiments. In some embodiments, the fins arepositioned circumferentially around the cutting surface. In someembodiments, the cutting table is coupled to a substrate to form acutter. The fins are formed either after or during the formation of thecutting table.

U.S. Pat. No. 9,175,521 discloses a cutting table including a cuttingsurface, an opposing surface, a cutting table outer wall, and one ormore slots. The cutting table outer wall extends from the circumferenceof the opposing surface to the circumference of the cutting surface. Theslots extend from a portion of the cutting surface to a portion of thecutting table outer wall. The cutting table is leached to form athermally stable cutting table. One or more slots are positioned inparallel with at least another slot in some embodiments. In someembodiments, the slots are positioned circumferentially around thecutting surface. In some embodiments, at least one slot is backfilledwith a backfilling material to increase heat transfer or impactresistance. In some embodiments, the cutting table is coupled to asubstrate to form a cutter. The slots are formed either after or duringthe formation of the cutting table.

US 2016/0130881 discloses a cutting element for use with a bit includingan obtuse cutting edge. The cutting edge may be formed between a cuttingface and a slanted face of the cutting element. The obtuse cutting edgemay be pre-formed in the cutting element for use with a bit used to milla window in casing and/or drill a deviated borehole. The cutting elementmay be positioned on the bit as a trailing cutting element, and orientedto cause the obtuse cutting edge to engage casing and/or a rockformation.

SUMMARY OF THE DISCLOSURE

The present disclosure generally relates to a superhard cutter withspikes. In one embodiment, a cutter for use with a drill bit includes: asubstrate for mounting in a pocket of the drill bit and made from acermet material; and a cutting table made from a polycrystallinesuperhard material, mounted to the substrate, and including a set ofspikes formed along at least a portion of a side of the cutting table.Each spike has an apical edge extending above a working face of thecutting table and converging toward the working face as the spikeextends from the side of the cutting table across at least a portion ofthe working face. Each spike has a pair of base edges converging towardthe apical edge as the spike extends from the side of the cutting tablethereacross, thereby forming a progressively wider gap between adjacentspikes.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

FIGS. 1A-1D illustrate manufacture of a superhard cutter with a set ofspikes and channels, according to one embodiment of the presentdisclosure.

FIG. 2A illustrates leaching of the cutter. FIG. 2B illustrates analternative cutter having a second set of spikes and channels, accordingto another embodiment of the present disclosure. FIG. 2C illustrates asecond alternative cutter having a knob for orientation thereof.

FIGS. 3A-3D illustrate the finished shaped cutter.

FIG. 4A illustrates brazing the shaped cutter into a blade of a drillbit. FIG. 4B illustrates the drill bit. FIG. 4C illustrates cuttingaction of the drill bit.

FIGS. 5A-5B illustrate manufacture of a third alternative superhardcutter with a set of spikes and passages, according to anotherembodiment of the present disclosure.

DETAILED DESCRIPTION

FIGS. 1A-1D illustrate manufacture of a superhard cutter 1 (FIG. 3A)with a set 2 of spikes 3 and channels 4, according to one embodiment ofthe present disclosure. Referring to FIG. 1A, the manufacturing processmay commence by placement of a shear cutter 5 into a laser cuttermachine 6. The shear cutter 5 may include a cylindrical cutting table 7mounted to a cylindrical substrate 8. The cutting table and substratemay be circular-cylindrical (shown) or elliptic-cylindrical (not shown).The cutting table 8 may be made from a superhard material, such aspolycrystalline diamond (PCD), and the substrate may be made from a hardmaterial, such as a cermet, thereby forming a compact, such as apolycrystalline diamond compact. The cermet may be a cemented carbide,such as a group VIIIB metal-tungsten carbide. The group VIIIB metal maybe cobalt. The shear cutter 5 may be manufactured by a high pressure,high temperature (HPHT) sintering operation using either a belt press ora cubic press.

Referring to FIG. 1B, the laser cutter machine 6 may be operated toremove selected PCD material from the cutting table 7 until the spikes 3are formed therein 7 a. Referring to FIG. 1C, the laser cutting machine6 may continue to remove selected PCD material from the cutting table 7a until the channels 4 are formed between adjacent spikes 3 therein 7 b.

Referring to FIG. 1D, the cutter 5 a may be repositioned in the lasercutting machine 6 and the machine operated remove selected cermetmaterial from the substrate 8 until a keyway 9 is formed therein 8 a fororienting the spikes 3 when mounting the cutter 1 in a drill bit 10(FIG. 4B). The keyway 9 may be located at an edge of the substrate 8 aand may extend from a back face thereof along a portion of a sidethereof. The keyway 9 may be a slot inclined relative to a longitudinalaxis of the cutter 1 by an angle ranging between ten and seventydegrees. The slot may have a width corresponding to a diameter of amating key (not shown) formed in a cutter pocket of the drill bit 10.The keyway 9 may be angularly offset from the set 2, such as beinglocated opposite therefrom. The laser cutting machine 6 may also beoperated to form a chamfer in the back face of the substrate 8 a.

Alternatively, the set 2 may be formed by using an electrical dischargemachine (EDM) instead of the laser cutting machine 6. Alternatively, thekeyway 9 and the chamfer may be formed by the EDM or by grinding.

FIG. 2A illustrates leaching of the cutter 5 b. The cutter 5 b may beremoved from the laser cutting machine 6. A portion of the substrate 8 aand a portion of the cutting table 7 b adjacent to the substrate may bemasked 11. A portion of the cutter 5 b including the cutting table 7 band the masked portion of the substrate 8 a may then be submerged into abath of acid 12, such as Aqua regia, and left therein for a soakingtime. The soaking time may be sufficient for the acid 12 to leach atleast a substantial portion of catalyst from the exposed portion of theleached cutting table 7 c. The acid 12 may penetrate into a working face13 w and a side 13 s of the cutting table 7 c, thereby increasing athermal stability thereof. The catalyst may be the same group VIIIBmetal as the substrate.

FIG. 2B illustrates an alternative cutter 14 having a second set 15 ofspikes 3 and channels 4, according to another embodiment of the presentdisclosure. The alternative cutter 14 may be similar to the cutter 1except that the laser cutting machine 6 or EDM has been operated to formthe second set 15 in a cutting table 14 t thereof. The second set 15 maybe angularly offset from the set 2, such as located opposite to the set2 (one-hundred eighty degrees therefrom). Further, a substrate (notshown) of the alternative cutter 14 may accordingly have a second keywaycorresponding to the second set 15. Upon retrieval of a drill bit havingthe alternative cutters 14 from the wellbore, the drill bit may beinspected for wear. Should a wear flat be observed on any of thealternative cutters 14, the worn alternative cutter may be de-brazedfrom the respective cutter pocket and rotated, such as by one-hundredeighty degrees, so that the unused set 2, 15 is moved to an operativeposition and then the cutter re-brazed to the drill bit, therebyextending the service life of the alternative cutters 14.

Alternatively, the alternative cutter 14 may have three sets of spikes 3and channels 4, spaced one-hundred twenty degrees apart, and a substratethereof may have a third keyway corresponding to the third set.

FIG. 2C illustrates a second alternative cutter 16 having a knob 17 fororientation thereof. The second alternative cutter 16 may include thecutting table 7 c mounted to an alternative substrate 16 s. Thealternative substrate 16 s may have the knob 17 mounted to a back face16 b thereof for orienting the set 2 of spikes 3 and channels 4. Thealternative substrate 16 s may be similar to the substrate 8 a exceptfor having the knob 17 mounted thereto instead of the keyway 9 formedtherein. The knob 17 may be formed separately from the rest of thesecond alternative cutter 16 and then mounted to the substrate 16 sthereof, such as by brazing. The knob 17 may be angularly offset fromthe set 2, such as being located opposite therefrom (one-hundred eightydegrees therefrom). The knob 17 may be hemi-spherical and have adiameter ranging between twenty-five and forty-five percent of adiameter of the back face 16 b. Instead of a key, the drill bit 10 mayhave a dimple (not shown) formed in the cutter pocket thereof for matingwith the knob, thereby ensuring that the second alternative cutter 16has been properly oriented to the operative position. The knob 17 may bemade from the same material as the substrate or a different materialthan the substrate, such as a metal or alloy, such as steel.

Alternatively, the second alternative cutter 16 may include thealternative cutting table 14 t and the second alternative cutter mayfurther include a second knob (not shown) mounted to the back face 17 bof the alternative substrate 16 s for orienting the second set 15.Alternatively, the knob 17 may be formed integrally with the alternativesubstrate 16 s.

FIGS. 3A-3D illustrate the finished shaped cutter 1. The set 2 mayinclude the plurality of the spikes 3 (ten shown) and the plurality ofthe channels 4 (nine shown) formed between adjacent spikes. Each spike 3may have a triangular front face, such as isosceles, forming a portionof the side 13 s of the cutting table 7 c. Each spike 3 may extend abovethe working face 13 w of the cutting table 7 c to an apical edge 3 a.Each apical edge 3 a may have a maximum height at the side 13 s and eachapical edge may converge toward the working face 13 w at an angle 18 asthe respective spike 3 extends from the side 13 s across the workingface 13 w. Each apical edge 3 a may be parallel with the rest of theapical edges of the set 2. Each apical edge 3 a may be slightlytruncated to form a flat or may be rounded. The flat may a width rangingbetween twenty and one hundred fifty microns and the round may have aradius equal to one-half the width of the flat.

Each spike 3 may also have a pair of base edges 3 b and each base edgemay converge toward the respective apical edge 3 a as the respectivespike extends from the side 13 s across the working face 13 w, therebyresulting in each spike having a maximum width at the side. The inclinedapical edge 3 a and the converging base edges 3 b may create aprogressively wider gap between adjacent spikes 3 as the adjacent spikesextend from the side 13 s across the working face 13 w. Theprogressively wider gap may facilitate cuttings removal from the spikes3 as the cutter 1 engages a rock formation 19 (FIG. 4C). The inclinedapical edge 3 a and the converging base edges 3 b may result in eachspike having triangular side faces.

Each channel 4 may have a rectangular mouth formed in the side 13 s. Afloor of each channel may extend below the working face 13 w to amaximum depth at the side 13 s and a floor of each channel may convergetoward the working face 13 w at an angle (not shown) as the respectivechannel extends across the working face. Each channel 4 may serve totransport the leaching acid 12 into the cutting table 7 c, therebyincreasing penetration of the acid 12 therein. A width of each channel 4may be sized to create capillary action during leaching of the cuttingtable 7 c and may range between fifty and three hundred microns. Eachchannel 4 may be parallel with the rest of the channels of the set 2 andwith the apical edges 3 a of the set.

The set 2 may be formed along a portion of the side 13 s, such asbetween one-quarter to one-half of a circumference thereof. The set 2may extend from the side 13 s and across a portion of the working face13 w by a distance ranging between one-eighth and one-half of a diameterof the working face. A maximum height of the spikes 3 may vary along theset 2, such as having a parabolic distribution along the set with thetallest spike(s) at the center of the set and the shortest spikes at theperiphery of the set. A maximum width of the spikes 3 may vary inaccordance with the maximum height of the spikes 3 and the tallestspike(s) may have a maximum width corresponding to a spacing betweenadjacent channels. A maximum height of the tallest spike(s) 3 may rangebetween one-half and three millimeters.

A depth of the channels 4 may vary along the set 2, such as having aparabolic distribution along the set with the deepest channel(s) at thecenter of the set and the shallowest channels at the periphery of theset. A maximum depth of the deepest channel(s) 4 may be limited toensure a buffer 20 is maintained between the channel(s) and an interface21 between the cutting table 7 c and the substrate 8 a. The depth of thechannels 4 may correspond to the height of the adjacent spikes 3. Thebuffer 20 may have a height from the interface 21 ranging betweenone-half and one millimeter. A spacing between adjacent channels 4 maybe uniform for the set and may range between one-half and fivemillimeters. A spacing in a lesser portion of the range may ensure thata foundation portion of the cutting table 7 c adjacently below eachspike 3 beneath each spike is completely leached; however, a spacing inthe greater portion of the range may be more advantageous for tougherrock formations.

Alternatively, a maximum height of the spikes 3 and/or a maximum depthof the channels 4 may be uniform. Alternatively, the channels 4 may befilled after leaching with a ceramic, such as molybdenum carbide,titanium carbide, vanadium carbide, iron carbide, nickel carbide,niobium carbide, and tungsten carbide. Alternatively, each apical edge 3a may be sharp or may include a pair of inclined surfaces.

FIG. 4A illustrates brazing the shaped cutter 1 into a blade 22 of adrill bit 10. The brazing operation may be manual or automated. Aplurality of the cutters 1 may be mounted into pockets formed in aleading edge of the blade 22. Each shaped cutter 1 may be delivered tothe pocket by an articulator 23. The articulator 23 may retain thecutter 1 only partially in the pocket such that the keyway 9 and key donot engage.

Once delivered, a brazing material 24 may be applied to an interfaceformed between the respective pocket and the shaped cutter 1 using anapplicator 22. As the brazing material 24 is being applied to theinterface, the articulator 23 may rotate the shaped cutter 1 relative tothe pocket to distribute the brazing material 20 throughout theinterface. The articulator 23 may then be operated to align the keyways9 with the key and engage the aligned members, thereby ensuring that theshaped cutter 1 is properly oriented to the operative position. Theoperative position may be where the apical edge 3 a of the tallestpeak(s) 3 is perpendicular to a projection (not shown) of the leadingedge of the respective blade 22 through the leading cutter pocket.

A heater (not shown) may be operated to melt the brazing material 24.Cooling and solidification of the brazing material 24 may mount theshaped cutter 1 to the blade 22. The brazing operation may then berepeated for mounting additional shaped cutters 1 into additionalpockets formed along the leading edge of the blade 22. The pocket may beinclined relative to a bottom face of the blade adjacent thereto by aback rake angle 25 (FIG. 4C).

FIG. 4B illustrates the drill bit 10. The drill bit 10 may include a bitbody 26, a shank 27, a cutting face, and a gage section 28. A lowerportion of the bit body 26 adjacent to the cutting face may be made froma composite material, such as a ceramic and/or cermet body powderinfiltrated by a metallic binder and an upper portion of the bit bodyadjacent to the shank 27 may be made from a softer material than thecomposite material of the upper portion, such as a metal or alloyshoulder powder infiltrated by the metallic binder. The bit body 26 maybe mounted to the shank 27 during molding thereof. The shank 27 may betubular and made from a metal or alloy, such as steel, and have acoupling, such as a threaded pin, formed at an upper end thereof forconnection of the drill bit 10 to a drill collar (not shown). The shank27 may have a flow bore formed therethrough and the flow bore may extendinto the bit body 26 to a plenum thereof. The cutting face may form alower end of the drill bit 10 and the gage section 28 may form an outerportion thereof.

Alternatively, the bit body 26 may be metallic, such as being made fromsteel, and may be hardfaced. The metallic bit body may be connected to amodified shank by threaded couplings and then secured by a weld or themetallic bit body may be monoblock having an integral body and shank.

The cutting face may include one or more primary blades 22 p, one ormore secondary blades 22 s, fluid courses formed between the blades, theleading cutters 1, and backup cutters 5. The cutting face may have oneor more sections, such as an inner cone, an outer shoulder, and anintermediate nose between the cone and the shoulder sections. The blades22 may be disposed around the cutting face and each blade may be formedduring molding of the bit body 26 and may protrude from a bottom of thebit body. The primary blades 22 p and the secondary blades 22 s may bearranged about the cutting face in an alternating fashion. The primaryblades 22 p may each extend from a center of the cutting face, acrossthe cone and nose sections, along the shoulder section, and to the gagesection 28. The secondary blades 22 s may each extend from a peripheryof the cone section, across the nose section, along the shouldersection, and to the gage section 28.

Each blade 22 may extend generally radially across the cone (primaryonly) and nose sections with a slight spiral curvature and along theshoulder section generally longitudinally with a slight helicalcurvature. Each blade 22 may be made from the same material as the bitbody 26. The leading cutters 1 may be mounted into the pockets alongleading edges of the blades 22 and the backup cutters 5 may be mountedinto pockets adjacent to trailing edges of the blades. The backupcutters 5 may be omitted from the cone sections of the primary blades 22p. One of the leading cutters in each blade 22 adjacent to the gagesection 28 may be the shear cutter 5 (shown) or the shaped cutter 1 (notshown).

One or more ports 29 may be formed in the bit body 26 and each port mayextend from the plenum and through the bottom of the bit body todischarge drilling fluid (not shown) along the fluid courses. Once thecutters 1 have been mounted to the respective blades 22, a nozzle (notshown) may be inserted into the each port 29 and mounted to the bit body26, such as by screwing the nozzle therein.

The gage section 28 may define a gage diameter of the drill bit 10. Thegage section 28 may include a plurality of gage pads, such as one gagepad for each blade 22 and junk slots formed between the gage pads. Thejunk slots may be in fluid communication with the fluid courses formedbetween the blades 22. The gage pads may be disposed around the gagesection 28 and each pad may be formed during molding of the bit body 26and may protrude from the outer portion of the bit body. Each gage padmay be made from the same material as the bit body 26 and each gage padmay be formed integrally with a respective blade 22. Each gage pad mayextend upward from a shoulder portion of the respective blade 22 to anexposed outer surface of the shank 27.

FIG. 4C illustrates cutting action of the drill bit 10. In use (notshown), the drill bit 10 may be assembled with one or more drillcollars, such as by threaded couplings, thereby forming a bottomholeassembly (BHA). The BHA may be connected to a bottom of a pipe string,such as drill pipe or coiled tubing, thereby forming a drill string. TheBHA may further include a steering tool, such as a bent sub or rotarysteering tool, for drilling a deviated portion of the wellbore. The pipestring may be used to deploy the BHA into the wellbore. The drill bit 10may be rotated, such as by rotation of the drill string from a rig (notshown) and/or by a drilling motor (not shown) of the BHA, while drillingfluid, such as mud, may be pumped down the drill string. A portion ofthe weight of the drill string may be set on the drill bit 10. Thedrilling fluid may be discharged by the nozzles and carry cuttings up anannulus formed between the drill string and the wellbore and/or betweenthe drill string and a casing string and/or liner string.

The inclination angle 18 of each cutter 1 may correspond to a back rakeangle 25 of the cutters 1, 5 such that the apical edges 3 a may beperpendicular or substantially perpendicular to the rock formation 19engaged by the spikes 3 during drilling. Each of the inclination angle18 and the back rake angle 25 may range between ten and thirty degrees.As the drill bit 10 engages the rock formation 19 adjacent to thewellbore, each leading cutter 1 may gouge and/or crush 30 the formation,thereby facilitating subsequent shear cutting by the respective backupcutter 5.

FIGS. 5A-5B illustrate manufacture of a third alternative superhardcutter 31 with a set of spikes 3 and passages 32, according to anotherembodiment of the present disclosure. Referring to FIG. 5A, themanufacturing process may commence by placement of the shear cutter 5into the laser cutter machine 6 (see FIG. 1A). The laser cutter machine6 may be operated to remove selected PCD material from the cutting table7 until the spikes 3 are formed therein 33 a. Instead of the channels 4,the laser cutting machine 6 may be positioned and operated to bore aleaching passage 32 underneath each spike 3 from the working face 13 wto the side 13 s of the cutting table 33 a.

Each leaching passage 32 may have a front port at the working face 13 wof the cutting table 33 and a side port 32 s at the side 13 s thereof.Each leaching passage 32 may extend outward and backward from the frontport to the side port 32 s. A depth of the side ports 32 s may beuniform along the set. A maximum depth of the side ports 32 s may belimited to ensure that the buffer 20 is maintained between the leachingpassages 32 and the interface between the cutting table 33 a and thesubstrate 8 a. The depth of the side ports 32 s may correspond to theheight of the tallest spike 3. The location of each front port maycorrespond to an inner end of the respective spike 3. An inclinationangle of each leaching passage 32 relative to the working face 13 w mayrange between five degrees and forty-five degrees. A diameter of eachleaching passage 32 may range between one hundredth of a millimeter andone millimeter.

Alternatively, the depth of the side ports 32 s may vary with the heightof the spikes 3 along the set similar to the channels 4. Alternatively,the depth of the side ports 32 s may be uniform at a depth correspondingto the height of any of the spikes 3 in the set.

The third alternative superhard cutter 31 may be repositioned in thelaser cutting machine 6 and the machine operated remove selected cermetmaterial from the substrate 8 until the keyway 9 and chamfer are formedtherein 8 a (or alternatives discussed above).

Referring to FIG. 5B, the third alternative superhard cutter 31 may beremoved from the laser cutting machine 6. A portion of the substrate 8 aand a portion of the cutting table 33 a adjacent to the substrate may bemasked 11. A portion of the third alternative superhard cutter 31including the cutting table 33 a and the masked portion of the substrate8 a may then be submerged into the bath of acid 12 and left therein fora soaking time. The soaking time may be sufficient for the acid 12 toleach at least a substantial portion of catalyst from the exposedportion of the leached cutting table 33 b. Leaching is facilitated bythe inclusion of the leaching passages 32.

Alternatively, the third alternative superhard cutter 31 may include asecond (or more) set of spikes, as discussed above for the alternativecutter 14. Additionally, a plurality of the third alternative superhardcutters 31 may be used with the drill bit 10 instead of the shapedcutters 1.

While the foregoing is directed to embodiments of the presentdisclosure, other and further embodiments of the disclosure may bedevised without departing from the basic scope thereof, and the scope ofthe invention is determined by the claims that follow.

1. A cutter for use with a drill bit, comprising: a substrate formounting in a pocket of the drill bit and made from a cermet material;and a cutting table made from a polycrystalline superhard material,mounted to the substrate, and comprising a set of spikes formed along atleast a portion of a side of the cutting table, wherein: each spike hasan apical edge extending above a working face of the cutting table andconverging toward the working face as the spike extends from the side ofthe cutting table across at least a portion of the working face, andeach spike has a pair of base edges converging toward the apical edge asthe spike extends from the side of the cutting table thereacross,thereby forming a progressively wider gap between adjacent spikes. 2.The cutter of claim 1, wherein: the set further comprises a plurality ofchannels formed in the side of the cutting table, each channel is formedbetween adjacent spikes, and a width of each channel is sized to inducecapillary action of leaching acid.
 3. The cutter of claim 2, wherein afloor of each channel converges toward the working face as the channelextends from the side of the cutting table thereacross.
 4. The cutter ofclaim 3, wherein a maximum depth of the channels varies along the set.5. The cutter of claim 4, wherein a deepest one or more of the channelsis located at a center of the set and shallowest ones of the channelsare located at the periphery of the set.
 6. The cutter of claim 1,wherein each apical edge is parallel with the rest of the apical edgesof the set.
 7. The cutter of claim 1, wherein the set extends across theworking face by a distance ranging between one-eighth and one-half of adiameter of the working face.
 8. The cutter of claim 1, wherein amaximum height of the spikes varies along the set.
 9. The cutter ofclaim 8, wherein a tallest one or more of the spikes is located at acenter of the set and shortest ones of the spikes are located at theperiphery of the set.
 10. The cutter of claim 8, wherein a tallest oneor more of the spikes has a height ranging between one-half and threemillimeters.
 11. The cutter of claim 1, wherein the set of spikesextends along the side for a distance ranging between one-quarter toone-half of a circumference of the side.
 12. The cutter of claim 11,wherein the substrate has a keyway formed in an edge thereof fororienting the set of spikes.
 13. The cutter of claim 11, wherein thesubstrate has a bump formed in or mounted to a back face thereof fororienting the set of spikes.
 14. The cutter of claim 11, wherein thecutting table further comprises a second set of spikes formed along asecond portion of the side of the cutting table.
 15. The cutter of claim1, wherein: the set further comprises a plurality of leaching passages,and each leaching passage extends underneath a respective spike.
 16. Thecutter of claim 15, wherein each leaching passage has a front port atthe working face of the cutting table and a side port at the side of thecutting table.
 17. The method of claim 16, wherein a depth of each sideport corresponds to a height of one of the spikes.
 18. The cutter ofclaim 15, wherein a diameter of each leaching passage ranges between0.01 mm and 1 mm.
 19. The method of claim 15, wherein an inclinationangle of each leaching passage relative to the working surface of thecutting table ranges between 5 degrees and 45 degrees.
 20. A bit fordrilling a wellbore, comprising: a shank having a coupling formed at anupper end thereof; a body mounted to a lower end of the shank; and acutting face forming a lower end of the bit and comprising: a bladeprotruding from the body; and the cutter of claim 1, wherein: thesubstrate is mounted in the pocket formed in the blade at a back rakeangle, and an inclination angle of each apical edge corresponds to theback rake angle such that the interface is perpendicular orsubstantially perpendicular to a rock formation engaged by the spikesduring drilling.